The present invention relates to noise filters usable in various apparatus such as apparatus for communication, OA and games, to connectors usable for cables and terminal devices, and to multi-level structures used for such devices. More specifically, the present invention relates to wideband thin noise filters for removing high frequency noise, and wideband, expanded function connectors.
The increase in broadcast output, the increase of illegal radio devices and the wide spread use of high frequency devices are all factors deteriorating the electromagnetic environment today.
Among various measures against high frequency noises, a filter using a coil is popular. Moreover, the recent demand for smaller and more uncostly electronic devices is directed to the filter, too.
When a conventional magnetic material is employed, the attenuation decreases sharply in the high frequency region, due to resonance, as compare with a desired attenuation level, as shown by a one dot chain line 34 in FIG. 2.
When a lead wire is wound around the conventional thin film magnetic material, the magnetic material in the form of the thin film is liable to bend.
In the case of a manually wound lead wire, the winding condition is irregular. This irregularity increases the nonuniformity of the characteristic especially in the high frequency region.
Furthermore, as to the filter for a high frequency region, there still remains the following technical tasks unsolved. (i) No leakage inductance and low irregularity in inductance in pairs. (ii) Small Inter-winding capacitance. (iii) Small inter-channel crosstalk. (iv) High permeability and high resistance at high frequencies.
On the other hand, in PC (personal computer), and LAN, the transmission speed or data transfer rate is increased more or more, and the speed increase is also achieved in terminal devices. Relatively inexpensive electric wires and cables have problems in high speed transmission, and the trend is toward optical means.
However, the use of electric wires and cables, if appropriate for higher transmission, can reduce the total cost, and lower the power consumption by eliminating the need for O/E and E/O converters. Moreover, the merit of continuing the use of the existing transmission medium is significant.
A conventional IEEE1394 cable 51xe2x80x2 as shown in FIG. is a high speed PC interface adapted for high speed transmission (400 Mbps Max) such as high speed picture transmission.
However, the conventional IEEE1394 interface 51xe2x80x2 has the following technical problems. First, the transmission distance is limited (Standard: 4.5 m). This is said to be the influence of a power source line. However, even for a four core type having no power source line, the upper limit is 10 m (actually measured evaluation). Second, the handling is not easy because of its shield structure (A cable is thick and hard.). Third, the connector terminal treatment is complicated and costly because of the shield of the cable
It is an object of the present invention to provide a wideband noise then filter which is efficient in removing noise, small in signal attenuation, and small in size
It is another object of the present invention to provide a connector capable of expanding the transmission band and transmission distance.
According to the present invention, a wideband noise reducing device comprises: a magnetic member comprising at least one magnetic film; and first and second boards such as flexible printed circuit boards (FPC). The magnetic member is sandwiched between the first and second boards. Each of the first and second boards comprises a signal pattern portion. The signal pattern portions of the first and second boards are connected with each other to form a signal line wound around the magnetic member.